The present invention relates to shielded cable connections to prevent EMI and RFI leakage from the cable conductors, particularly at connection and terminal points within the cable system when such systems are not fully shielded externally but rather depend on internal shielding methods in which the shielded conductor is terminated to the shell or backshell of the cable system.
In the past termination of the shield on the cable has been done by connecting the shield to the backshell via a conductor segment, usually a pigtail type of conductor, a plate member, or a ring structure. In the case of the pigtail type of connection between cable shield and exterior shell of the cable system, multiple cables necessitate separate shield terminations, and typically there is always some EMI opening that is not shielded around the cable since this type of connection is not fully circumferential. The various conventional fillers and insulation used for strain relief clamping between the cables and the shell structure do not provide the necessary shielding. In those cases where a plate structure is used, such as shown in U.S. Pat. No. 4,447,100 and U.S. Pat. No. 4,382,653, there is usually a free space existing between the cable and the shell structure despite the presence of the connecting plates so that EMI leakage is possible via the spacing between the plate structures. Further, such rigid connecting structures are vulnerable to cracking and breaking over time, thus further contributing to EMI leakage. Finally, in those cases where a clamping ring structure is used, such as shown in U.S. Pat. No. 3,598,895, the same defects as described in the case of plate structures are present and indeed are even compounded by the absence of a reasonable intervening space between the cable and the exterior shell structure, so that shielding is inhibited by the close proximity of shell structure and cable. There is a need therefore to provide a shielded terminal connection for cables which allows for simple construction at a low cost and which virtually assures complete EMI shielding without leakage.